This present disclosed subject matter relates to techniques for imaging and detecting the propagation of mechanical waves within a body structure of a patient.
Certain medical conditions, such as diagnosis of myocardial ischemia, can be difficult to establish in their early stages when treatment is most effective. Patients suffering from myocardial ischemia can present to an emergency room or acute care facility with typical cardiac symptoms such as chest pain, described as tightness, pressure, or squeezing, but some patients can have other symptoms such as arm or chin pain, nausea, sweating, or abdominal pain. Certain techniques such as electrocardiogram often provide inconclusive findings regarding ischemia, and sometimes can even be unable to identify situations in which ischemia has progressed to cell damage and myocardial infarction (MI). Other techniques are available for diagnosing infarction relative to its predecessor, ischemia. For example, a blood test to measure the creatine kinase-MB (CK-MB) enzyme level is used for detection of myocardial cell damage. Other serum markers include troponin I, and to a lesser extent, myoglobin. However, the blood levels of certain such compounds can take several hours to rise, so that diagnosis of MI can be delayed. Reliance on blood tests alone can result in a significant loss of time when early aggressive therapy is warranted.
Certain less invasive diagnostic techniques have become available through the observation of mechanical properties of tissue via imaging techniques. Such evaluation of the function of the heart, cardiovascular tissue, or other body structures can be based on the mechanical interpretation of the movement of the these structures, such as, for example, the active contractions and passive relaxation of the myocardium.
Using certain imaging techniques, the evaluation of the heart function can be based on a single mechanical interpretation of myocardial deformation. By use of these techniques, the deformations of the myocardium can be quantified over a complete cardiac cycle in order to provide some information on the myocardial viability.
Certain low frequency mechanical vibrations in the heart are known in human patients. Certain ultrasound techniques can be used to obtain pulsive mechanical vibrations around end-systole and end-diastole in the frequency range of 25 to 100 Hz.
Additionally, atrial arrhythmias are a known and can cause of morbidity and mortality. Certain mechanical factors, such as chamber size and wall tension, can affect the onset and perpetuation of atrial arrhythmia. Certain echocardiographic measurements can also be used to characterize atrial arrhythmias. Yet, systems and techniques to analyze the 2-D spatio-temporal evolution of the local deformations of the atria during e.g., focal tachycardia, flutter, and fibrillation, would be beneficial.
Accordingly, there is a need for a noninvasive imaging modality which provides insight into the source or focus of an arrhythmia.